The easiest way to build a quality garden shed in New Zealand is to use one of the kit set sheds supplied by companies like Trade Tested for example. These sheds are pretty easy for the average home handyman to assemble, and the finished product is attractive and sturdy easy to use.
An essential first step is to build the floor for the shed, this can present a bit of a challenge if the ground is sloping. Normally on flat ground when you would use a concrete pad or a wooden floor, but on the sloping ground, it is almost always preferable and easiest to use a wooden floor set on posts. These need to be spaced at 1.5 metre intervals up the slope and 0.5 metre intervals along a slope (the joists will be spaced at around .5 metre intervals).The posts will need to be concreted into the ground although for a shed they do not need to be set deep.
The posts also need to be set level to support the joists that go under the flooring. The easiest way to get the posts level is to get one edge of the flooring level, then cut the post to be a few centimetres shorter than the depth of a hole and half fill the hole with wet concrete. The post can be jiggled into place using a spirit level to check the exact height off the fixed edge. It is well worth spending time on this step to get everything correct and level.
Once the concrete is sufficiently set after a few hours then the joists can be mounted on top of the posts and nailed or bolted into place. The trade tested sheds come and convenient sizes wood flooring in multiples of 1.5 metres, and the easiest and cheapest way to put flooring down for a large shed is 2 years 1.5 metre by 150 centimetre fence palings, 19 centimetre thickness will suffice. This makes it easy to leave a rebate around the edge of the floor for mounting the shed walls and ensuring that the floor as above the base of a shed, and is hence watertight and dry.
Here’s a video on how to build a shed on flat ground:
Video: Build Your Own Backyard Shed
You may also want to place a concrete pad and front of your shed and this should be done prior to assembling the kit set shed.